Animal diversity Terms Flashcards
(131 cards)
Diplontic life cycle
refers to the life cycle of organisms, which is dominated by the diploid stage.
Asymmetry
is the absence of, or a violation of, symmetry
Radial symmetry
symmetry in which the body is shaped like a pie or barrel (lacks a left and right side) and can be divided into mirror imaged haves by any plane through its central axis
Oral–Aboral axis
cnidarians have this
single body axis- have their mouth on the oral surface and their opposite side is the aboral surface
Bilateral symmetry
A central longitudinal plane divides the body into 2 equal but opposite halves
Cephalization
evolutionary trend toward the concentration of sensory equipment at the anterior end of the body)
Anterior
front
posterior
back
dorsal
top
ventral
bottom
Diploblastic
having only 2 germ layers
germ layers means tissues
Triploblastic
Having 3 germ layers: the endoderm mesoderm and ectoderm; most eumetazoans are this
Endoderm
the innermost germ layer, lines the pouch that forms during gastrulation (the archenteron) and gives rise to the lining of the digestive tract and organs such as liver lungs of vertebrates
Mesoderm
The middle primary germ layer in a triploblastic animal(bilaterally symmetrical animals) embryo that forms after gastrulation which fills the space between the ecto and endoderm that develops into the notochord the lining of the coelom muscles skeleton gonads kidneys and most of circulatory system (most organs between digestive tract and outer covering of the animal)
Ectoderm
the outermost of the 3 primary germ layers; covering the surface of the embryo gives rise to outer covering of animal and in some phlya the central nervous system, inner ear and lens of the eye
Coelom
true body cavity- found in large animals(called coelomates) - a body cavity between the digestive tract (derived from the endoderm) and the outer body wall (ectoderm); Forms from tissue derived from the mesoderm
Acoelomate
some triploblastic animals are compact and lack a body cavity
Small and or flat animals that don’t require internal transport and circulation system instead rely on diffusion
archenteron just vanishes
Pseudocoelomate
Animals with only a hemocoel
(Eu)coelomate
any animal that has a true coelom (fluid filled body cavity) which surrounds the gut and is lined on both sides by mesoderm.
True Tissue
eumetazoans
Segmentation
is the division of some animal and plant body plans into a series of repetitive segments
Determinate development
A type of embryonic development in protostomes that rigidly casts(determines) the developmental fate of each embryonic cell very early
Deuterostome
deuteros= second)
in animals a developmental mode distinguished by the development of the anus from the blastopore; also characterized by radial and indeterminate cleavage and by the body cavity forming as out pockets of mesodermal tissue
Schizocoely
the process by which protostome animal embryos develop; it occurs when a coelom (body cavity) is formed by splitting the mesodermal embryonic tissue